Surefire Optimized Bolt Carrier

[Tokarev]

The Surefire Optimized Bolt Carrier has been seen on YouTube and a few other places since 2016 and is apparently ready for commercial sale. Has anyone tried one yet?

Surefire says the OBC was designed by Jim Sullivan. Sullivan was one of the Armalite people back in the day.

The OBC uses a short buffer and an abbreviated gas key. This gives the carrier a quarter inch or so more travel. This extra travel gives the magazine more time to position the cartridge for feeding. Also the OBC has a spring-loaded counterweight in the carrier itself. This is supposed to delay unlocking and also "balance" the reciprocating mass and eliminate bolt bounce.

I like the theory of the OBC and am eager to give it a try. With that said, the $450 sticker price is pretty frightening. Too bad the package isn't priced somewhere around the $300 mark. Maybe $350.

https://www.surefire.com/optimized-bolt-carrier-group-556mm.html




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[Jay Cunningham]

hmm

Neat, but hard to justify... at least for my needs.

[Dan_S]

I’m very interested in this, and your thoughts once you have one in hand.

[jbrimlow]

What problems is this designed to solve, other than bolt bounce? Is it just supposed to be a 'better mousetrap'?

[MSparks909]

Unless you’re running full auto and/or a suppressor I don’t think it’s worth the cost. If you want a revised cam pin track and an updated bolt get the full LMT E-Carrier BCG.

[Tokarev]

Unless you’re running full auto and/or a suppressor I don’t think it’s worth the cost. If you want a revised cam pin track and updated bolt get the full LMT E-Carrier.
I think the lengthened stroke is probably what this product brings to the table over whatever else is out there.

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[MSparks909]

I think the lengthened stroke is probably what this product brings to the table over whatever else is out there.

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I agree. And I think that benefit manifests itself most when used on suppressed full auto SBRs (ala the MK18). The increased stroke length gives the magazine more time to feed the next round and slows down the cyclic rate. On a semi-auto AR I don’t think you’ll notice much change vs a standard BCG/buffer combo

[Tokarev]

I agree. And I think that benefit manifests itself most when used on suppressed full auto SBRs (ala the MK18). The increased stroke length gives the magazine more time to feed the next round and slows down the cyclic rate. On a semi-auto AR I don’t think you’ll notice much change vs a standard BCG/buffer comboThe counterweight should delay bolt acceleration both from the locked position and at the end of the recoil stroke. Will the delay in dynamics lessen felt recoil?

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[ASH556]

I had the opportunity in 2017 to mess with this system back in 2017, so my memory's a little fuzzy. I didn't shoot it, but did get to tear it down and look at all the small parts as it interfaced in a gun. From what I recall what others are saying is correct. No real benefit to a semi-auto gun, but for FA, especially with a short barrel and suppressed it's a significant upgrade. I thought the one I examined had something different about the receiver too. A different cut/channel for the cam pin or something. Like I said, a little fuzzy.

I do remember thinking at the time, "This is what the 416 should have been." Basically, it addresses the issues of the Stoner system while not adopting the issues of direct-piston systems.

[Tokarev]

http://www.defensereview.com/surefire-optimized-bolt-carrier-long-stroke-obc-ls-drop-in-bcg-and-h7s-buffer-system-for-better-weapon-control-reliability-and-durability-best-tactical-ar-15m4m4a1-carbineshort-barreled-rifle/

[John Hearne]

It seems like a neat concept and is consistent with the points Sullivan brought up with the Forgotten Weapons guys.

Two issues. 1) It fills a fairly small niche. If you are shooting a suppressed Mk18 full auto then this seems like a really good idea. As you move away from that - longer barrel, no suppressor, no full auto - it seems to be less necessary. 2) The unanswered question is whether the increased length of bolt carrier group travel will result in broken bolt catches as seen in the 9mm SMG variants.

[Tokarev]

The unanswered question is whether the increased length of bolt carrier group travel will result in broken bolt catches as seen in the 9mm SMG variants.

Good question. Maybe that's why it took a couple years to get to market. Maybe Surefire was tweaking the weight to help prevent bolt stop breakage.

[Tokarev]

In stock here:

https://www.centurionarms.com/ProductDetails.asp?ProductCode=SF-OBC-556&mc_cid=029f7c6f67&mc_eid=ade0e45bf8

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[JclInAtx]

Inrange tv did an interview with Jim Sullivan and they discussed the bolt carrier as well as the extended capacity mags and had some video of full auto mag dumps. It was a while ago, and may have been multiple videos.
I think this is it but my phone isnt playing nice with it.
https://www.full30.com/watch/MTcx/interview-shooting-jim-sullivan-ar-15-designer

[spyderco monkey]

What problems is this designed to solve, other than bolt bounce? Is it just supposed to be a 'better mousetrap'?

The OBC is about 3 things primarily:

1. Reducing FA rate of fire for improved controllability. It cuts ROF from 850-900rpm to 600rpm, resulting in better controllability and less ammo consumption.

2. Reducing bolt impact. This was one of the principles behind Sullivan's Ultimax machinegun. The bolt has an additional 0.4" of travel, allowing more of its rearward energy to be absorbed by the buffer spring prior to the bolt bottoming out. This should reduce recoil/sight movement in both FA and Semi auto.

3. Improving magazine reliability. Reducing bolt cycle speed gives the magazine spring more time to raise the bullet into position. This is especially important for suppressed FA weapons, but also will likely improve the reliability of extra capacity magazines like the Surefire 60 - which was also designed by Sullivan.

https://www.recoilweb.com/wp-content/uploads/2018/03/Surefire_OBC01.jpg

https://www.recoilweb.com/watch-recoiltv-gun-room-surefire-obc-135516.html

And the original Jim Sullivan interview, showing the increase in controllability:
https://youtu.be/gOUKXIrDE0I?t=604